By Matthew Schmitz, M.D.
Question: How Will My Prostate Cancer Be Staged?
When your cancer is “staged,” your doctor is attempting to formally classify your cancer based on how far it has advanced. This is typically done after you have been diagnosed with prostate cancer following a PSA test or other examination.
The stage of your cancer is one of the most important factors used when determining your overall prognosis and which treatment option is the best for you. For the most part, the lower your stage, the less your cancer has progressed and the better the prognosis.
Virtually all prostate cancer patients undergo some level of staging and it is important to have a basic understanding of how this is accomplished.
Initial Questions and Tests
The first step in staging is accomplished when your physician performs a digital rectal examination. Nearly all men will undergo at least this level of staging. Often, the physician can feel how large the tumor itself is and whether the tumor is present in one or both halves (or lobes) of the prostate.
The answers you give to questions from your doctor about symptoms, such as bone pain (which may suggest that the cancer has spread to the bones), could also mean a higher stage of cancer is present.
Prostate cancer, when it spreads distantly from the prostate, often invades the bones. Because of this, one of the more common imaging tests used for staging prostate cancer is the bone scan (sometimes called a “radionuclide bone scan”).
To conduct a bone scan, you will need to have a small amount of radioactive liquid injected into a vein. This material will spread throughout the body, but will preferentially go to sites in the bone where cancer exists.
A few hours after the material is injected, you will lie on a table while a special camera is used that can detect where the radioactive material has collected. The areas of your body with the most radioactive material will “light up” on the camera.
Unfortunately, other diseases such as arthritis can also cause damage to the bones and will light up on a bone scan. Because of this, if you have areas on your bone scan that concern your physician, you may need more testing to fully determine whether cancer is present there or not.
Computed Tomography Scan (CT or CAT scan)
A CT scan uses X-rays to make a detailed image of the inside of your body. While you lie on a table, the table will slide in and out of a large ring that produces and detects the X-rays. Many X-rays are taken in a short amount of time, and then they are combined using computer software to make a set of “slices” that show structures within your body. You may or may not need to have a contrast liquid injected intravenously (I.V.) into a vein in order to achieve a better picture.
CT scans are helpful in detecting large, bulky tumors in the prostate or elsewhere. They are usually most helpful in determining if large amounts of your cancer have spread to other organs or to lymph nodes near the prostate. They are not particularly good at picking up small clumps of cancer cells throughout the body.
Magnetic Resonance Imaging (MRI) Scan
MRI scans do not use X-rays like CT scans. Instead, they use radio waves to produce a very detailed picture of the body. The images created by an MRI scan are “slices” of the body that can also be combined into a 3D model. You will need to lie on a table that then slides into a large tube for this exam. MRI scans usually take much longer than CT scans to complete, and you will be instructed to lie very still throughout the exam. Sometimes, as with CT scans, a liquid contrast material is needed in order to create a better image.
MRI scans are able to provide more detailed images of soft tissues such as lymph nodes, the prostate and other nearby structures like the seminal vesicles and bladder.
The ProstaScint scan is a relatively new development that uses a technique similar to a bone scan. A small amount of radioactive material is injected into your vein. This material travels to places where prostate cancer cells have spread. A special camera is used to create an image of your body with sites of prostate cancer cells. This is especially helpful when trying to determine if soft tissues (not bones) throughout the body have been invaded by prostate cancer cells.